A. Technical Field
The present invention relates generally to an active power switch control circuit and method for its implementation for one-wire applications.
B. Background of the Invention
In one-wire applications, a power management unit assists in maintaining the communication between an electronic device and an external source via a one-wire I/O interface. The one-wire I/O interface may serve as input port, output port and power supply port. Typically, the external source can only supply power when the input signal to the I/O interface is high. For optimum power management, properly turning off the power supply is necessary to prevent leakage when the external input signal is lower than the internal voltage level.
Various efforts have been made to improve the power switch controlling methods available for one-wire applications. In one example, a controllable switch may be coupled between the electronic device and the external source. The controllable switch may be switched on/off depending on a result from a comparison between the input voltage from the external source and an internal voltage within the electronic device. When the input voltage from the external source is below the internal voltage, the controllable switch is switched OFF to current flowing back toward the external source. To switch off the controllable switch, at least one threshold voltage difference is required, which may cause the power loss too large for desired power management performance.
It would be desirable to implement improved voltage comparison and switch control to reduce power loss within one-wire applications.